Furnace for chemical reactions.



M. SHOELD.

FURNACE FOR CHEMICAL REACTIONS.

APPLICATION FILED JAN. 28, I918.

Patented Aug. 6, 1918.

W Jc 62a 14/ J 74 Jay;

UN TED SATES PA I OFFICE.

MARK SHOELD, OF CHICAGO, ILLINOIS, ASSIGNOR T0 ARMOUR FERTILIZER WORKS, OF CHICAGO, ILLINOIS, A. CORPORATION OF NEW JERSEY.

FURNACE FOR CHEMICAL REACTIONS.

Specification of Letters Patent.

Patented Aug. 6, 1918.

Application filed January 28, 1918. Serial No. 214,054.

To all whom it may concern:

Be it known that 1, MARK SHOE'LD, a subject of the King of Sweden, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Furnaces for Chemical Reactions, of which the following is a specification.

Various types and styles of electric and other chemical furnaces have been proposed and constructed all of which have more or less objectionable or detrimental features, and the object of this invention is the production of a furnace of this character with certain unique and novel advantageous characteristics which overcome many of the ineflicient and undesirable features of the preceding ones. Such improved furnace, while especlally adapted for the production of aluminum nitrid, is, of course, not limited or restricted to such particular use, but for convenience the new structure will be described in connection with the production of this particular product.

In its preferred form, the furnace uses receptacles or containers for carrying the bodies of solid particles or pieces, which receptacles due to gravity slide through the furnace and in such transit pass through the heat-chamber heated preferably by electricity and conveniently by an electric arc in the compartment an sustained between sultable electrodes. These sliding boats, trays, or transporting boxes, which are of openwork or skeleton construction, travel through the furnace in one direction and the gas employed in the chemical reaction flows through the same passage in the opposite direction, passing through the contents of such trays, whereby the gas, preliminary to reaching the heat-chamber, may be heated by the solid material in such trays which has already passed through the heat zone and been chemically changed, and whereby the hot gas after leaviiig the heat zone may be employed to initially heat the material in the descending transporting receptacles before they reach the heat chamber.

1 A further feature of the invention resides in the construction of the furnace and its sliding carriers or trays, whereby the gas is caused to change its direction of travel in the heat chamber and consequently to thoroughly permeate the mass of solid pieces in one or more of the trays, thus effecting a complete and efiicient chemical reaction. It is practically needless to'state that a purpose of the nvention is the provision of a furnace of thls type, which, while simple 1n structure and hence relatively economical to manufacture, is efiicient in operation, and can be used for indeterminate periods without excessive deterioration or in ury, in other words, wlthout any more than a wear and tear which could be reasonably expected.

In the accompanying drawing forming a part of this specification, and throughout the various views of which like reference characters refer to the same parts, I have illustrated a simple and preferred embodiment of the invention, and to thisdrawin reference should be had in connection wit the following detailed description of the structure and the method of its operation.

In this drawing:

Figure 1 is a fragmentary, longitudinal, vert cal section through the furnace illustratlng among other things the electric-arc heat-chamber and a plurality of carriers loaded with the material, some of which is to be treated and some of which has already traversed the heat zone;

Fig. 2 is a cross-section on line 2-2 of Fig. 1;

Fig. 3 is a plan view of one of the unloaded sllding carriers, and

Fig. l 1s a plan view of a modified form of bottom wall or floor for the heat-chamber of the furnace.

As is clearly shown, the furnace has an inclined passage or conduit 10 therethrough which, at the center of the furnace, is enlarged upwardly at 11 to provide a heatcompartment heated by an electric-arc maintained between a pair of spaced, horizontal electrodes 12 and 13 which may be made of graphite, for example. Such passage and intermediate compartment are defined and bounded by a carbon or graphite lining 14 providing a smooth plane floor or bottom wall for the passage down which the carriers or trays ma easily slide, and surrounding such lining t e furnace has any suitable heatinsulating material 15. That portion or section of the carbon or raphite lining constituting the floor or ttom wall of the chamber 11 has a number of perforations or holes 16 through it communicating becomin low such chamber with a fiue17 which extends upwardly in an inclined direction beneath the floor of the upper portion of the passage 10, whereby'the hot gas flowing up such passage 17 transmits its heat to the inmaterial in the carriers in the passage a ove it.

Gas under pressure, such as pure nitrogen, or nitrogen slightly impure, but not containing any oxidizing agent, as, for instance, nitrogen having a small percentage or portion of carbon monoxid, is introduced through a pipe 18 into that portion of passage 10 below the chamber 11 and then flows upwardly, passing more or less through the bodies of material carried on the slida'ble trays or receptacles.

Each of such vices comprises a flat carbon or graphlte bottom 19 provided around its edge with spaced, upstanding, carbon or graphlte pins 20 constituting a retaining fence or wall around the receptacle or carrier. The bottom 19 of such boat is perforated or provided with holes 21 in the same relation to one another as the holes 16, so that when any particular carrier or tray is in the chamber 11 its bottom holes and those 16 of the lining, will be in substantial register or alinement, thereby establishing ready communication between passage 10 and the gas discharge flue 17 Each carrier is adapted to transport a charge or load of the mate rial to be treated, and, in the present instance, in the production of alluminum nitrid, such material comprises briquets composed of finely-divided or cofnminuted carbon and alumina cemented together by any suitable adhesive or binder.

The furnace is operated substantially as follows:

The trays or carriers loaded with such briquets are intermittently introduced into the upper portion of passage 10, without permitting an escape of gas by means well known in the art and unnecessary to illustrate, and such boats or carriers are also intermittently removed from the lower portion of the passage in asimilar way. Consequently, each carrier, in its downward. sliding travel reaches the heat-chamber and remains stationary therein a predetermined period sufficient to permit the desired chemical reaction to occur between its briquets and the gas under the heat of the electric arc. While the load of briquets is occupying this position in the chamber, the course of the gas necessarily changes as it passes through such briquets down through the holes 21 and 16, into the underlying passage 17, thus effecting a thorough dispersion of the gas throughout such load of solid material. At the same time, of course, the chemical reaction takes place aided by this thorough intermixture of the solid and gaseous incarriers or transporting degredients. Each charge of briquets is heated somewhat before it enters the heat-chamber by reason of the heat transmitted to it from below from the hot gas ascending flue 17 the two being in juxtaposition, as shown. Also, as the gas on leaving pipe 18 passes up conduit 10 through the charges of briquets on the various carriages which have already passed through the heat zone, the gas is preliminarily heated and the briquets at the same time cooled before delivery.

The travel of the carriers and their loads need not necessarily be intermittent'or interrupted but rather may be continuous, if desired, in which case it is preferable to have the bottom of the heating compartment provided with longitudinal slots 22 (Fig. 4:) instead of more holes, whereby the apertures in the bottoms of the carriers, will form sustained connections with the flue below. Under these circumstances, the slots, of course, are so located as to register with the tray holes.

It will be clear, therefore, to those skilled in this art, that the material to be treated travels through the furnace in batches or loads on conveyors or carriers and the appliance is so constructed that the gas is caused to pass through such batches of material, being substantially uniformly or evenly distributed throughout such material. This is brought about by a change of direction of the travel of the gas in the heat chamber so that the heating and uniform mixing of the briquets and gas take place simultaneously or more or less substantially so. It will be observed, furthermore, that the gas is heated preliminarily and likewise the briquets, each receiving heat from the other after the latter has passed through the heat chamber.

This invention clearly is not confined in its useful employment to an embodiment in all respects exactly like that presented because this appliance may be varied in many minor details without departure from the heart of the invention and without sacrificing any of its real and fundamental advantages. It is not absolutely necessary that the electric arc shall be in the heat-chamber, nor is the invention in its broader aspects limited to electrical heating.

I claim:

1. In a furnace structure of the character described, the combination of a heat-chamber, means to heat said chamber, a carrier adapted to convey a load of the material to be treated into and out of said chamber, and means to cause a flow'of gas independent of said heating means through said carrier load While in said chamber, substantially as described.

2. In a furnace structure of the character described, the combination of a heat-chamber, means to heat said chamber by an electric arctherein, a carrier adapted to convey a load of the material to be treated into and out of said chamber, and means independent of said heating means to cause a flow of gas through said carrier load While in said chamber, substantially as described.

3. In a furnace structure of the character described, the combination of an inclined chamber, means to heat said chamber, a carrier adapted to slide through said heat chamher by gravity and convey a load of the material to be treated through said chamber, and means to cause a flow of gas throu h said carrier load While in said chamber, su stantially as described.

4;. In a furnace structure of the character described, the. combination of a heat-chamber, means to heat said chamber, a carrier adapted to convey a load of the material to be treated into and out of said chamber, and means to cause a flow of gas independent of said heating means through said chamber and load and change its direction of flow in so doing, substantially as described.

5. In a furnace structure of the character described, the combination of a heat-chamber having a perforated wall, means to heat said chamber, a carrier adapted to convey a load of the material to be treated into and out of said chamber and constructed to permit gas to pass through its wall corresponding to the perforated Wall of said chamber, and means to cause a flow of gas independent. of said heating means through said heatchamber, said carrier load while in said chamber, and the two walls specified, substantially as described.

6. In a furnace-structure of the character described, the combination of a heat-chamber having a perforated wall, means to heat said chamber, a carrier adapted to convey a load of material to be treated into and out of said chamber and constructed to permit gas to pass through its wall corresponding to the perforated wall of said chamber, and means to cause a flow of gas through said heat-chamber, said carrier load while in said chamber, and the two Walls specified, said Walls being so located as to cause a change of direction of flow of the gas in order to pass through them, substantially as described.

7. In a furnace-structure of the character described, the combination of a heat-chamber having a perforated floor, means to heat said chamber, a carrier with a perforated bottom-wall adapted to convey a load of the material to be treated into and out of said chamber, and means to cause a flow of gas independent of said heating means into said chamber and out through the perforations of said carrier and chamber, substantially as described.

8. In a furnace structure of the character described, the combination of an inclined heat-chamber having a perforated floor, a

carrier with a perforated bottom-wall adapted to slide through said chamber and convey therethrough a load ofthe material to be treated, and means to cause a flow of gas into said chamber and out through the perforations of said carrier and chamber, sub stantially as described.

9. In a furnace structure of the character described, the combination of a heat-chamber having a passage leading thereto. and a perforated floor, a carrier with a perforated bottom-Wall adapted to convey a load of the material to be treated intoand out of said chamber, a flue beneath said passage, and means to cause a flow of gas through said chamber, the load of material in the chamber, the perforations of said floor and bottom-Wall, and said flue, whereby the heated gas in said flue may preliminarily heat the material of a carrier while in transit through said passage, substantially as described.

10. In a furnace structure of the character described, the combination of a heat-chamber having a perforated floor and an inclined passage leading to said chamber, a carrier with a perforated bottom-Wall adapted to convey a load of the material to be treated 'through said passage and chamber, the perforations of said chamber floor being in communication with a flue beneath said passage, and means to cause a flow of gas independent of said heating means through said chamber, the perforations of said floor and bottom-wall, and said flue, whereby the heated gas in the flue may heat the contents of said passage, substantially as described.

11. In a furnace structure of the character described, the combination of a heat-chamber, means to heat said chamber, a plurality of carriers adapted to successively convey loads of the material to be treated through said chamber, means to cause a flow of gas through said chamber, and the material therein, and means to preliminarily heat said gas by the heat of material which has passed through the heat-chamber, substantially as described.

12. In a furnace structure of the character described, the combination of a heat-chamber, means to heat said chamber, a plurality of carriers adapted to successively convey loads of the material to be treated through said chamber, means to cause a flow of gas through said chamber and the material therein, and means to preliminarily heat said gas by causing i t to pa'ss through material which h'as traversed said heat-chamber, substantially as described.

13. In a furnace structure of the character described, the combination of a heat-chamber, means to heat said chamber, a plurality of carriers adapted to successively convey loads of the material to be treated through said chamber, means to cause a flow of gas through said chamber and the material therein, and means to heat said material preliminary to its entrance into the heat chamber by the heat of gas WlllCll has traversed said chamber, substantially as described.

14. In a furnace structure of the character described, the combination of a heat-chamber, means to heat said chamber, a plurality of carriers adapted to successively convey 10 loads of the material to be treated through by the heat of material which has passed through the heat-chamber, and means. to heat said material preliminary to its entrance into the heat-chamber by the heat of the gas which has traversed said chamber, substantially as described.

', MARK SHOELD. 

